Configurable downlink and uplink channels for improving transmission of data by switching duplex nominal frequency spacing according to conditions

ABSTRACT

Transmission techniques using configurable channels for the downlink and/or uplink are described. In one aspect, the downlink channel and/or uplink channel may be independently selected for a terminal. The terminal may establish a connection with a base station on default downlink and uplink channels. Another downlink channel and/or another uplink channel may be selected based on various factors such as channel quality, loading, and interference. The terminal would then switch to the new downlink and/or uplink channel for communication. In another aspect, the base stations broadcast sector information used by the terminals for communication and/or channel selection. The sector information may include various types of information such as the available downlink and uplink channels, the frequencies of the available channels, the loading on the available channels, and QoS information. The terminals may select a sector, a downlink channel, and/or an uplink channel based on the sector information.

BACKGROUND

I. Field

The present disclosure relates generally to communication, and morespecifically to transmission techniques for a wireless communicationsystem.

II. Background

A wireless multiple-access communication system can concurrently supportcommunication for multiple terminals on the downlink and uplink. Thedownlink (or forward link) refers to the communication link from thebase stations to the terminals, and the uplink (or reverse link) refersto the communication link from the terminals to the base stations.

The system may utilize frequency division duplexing (FDD), which employsseparate frequencies for the downlink and uplink. A base station and aterminal may communicate via a frequency channel for the downlink (orsimply, a downlink channel) and a frequency channel for the uplink (orsimply, an uplink channel). Each frequency channel has a specificbandwidth and is centered at a specific frequency. The distance orspacing between the downlink and uplink channels is typically fixed andreferred to as the duplexing frequency. The base station transmits dataand signaling to the terminal on the downlink channel, and the terminaltransmits data and signaling to the base station on the uplink channel.

The base station may communicate with multiple terminals via the samepair of downlink and uplink channels. These terminals would then sharethe available radio resources. The same pair of downlink and uplinkchannels may also be used by a nearby base station for communicationwith other terminals. The transmissions to/from each base station maythen act as interference to the transmissions to/from the other basestation. The interference may adversely impact the performance of theterminals communicating with both base stations.

There is therefore a need in the art for techniques to transmit data ina manner to improve throughput and reduce interference.

SUMMARY

Transmission techniques using configurable channels for the downlinkand/or uplink are described herein. The configurable channels may resultin variable duplexing in an FDD system and may be viewed as a form ofdynamic frequency reuse.

In an embodiment, the downlink channel and/or uplink channel may beindependently selected for a terminal. The terminal may establish aconnection with a base station on default downlink and uplink channels.The default downlink and uplink channels may be provisioned at theterminal or conveyed by the base station. Another downlink channeland/or another uplink channel may thereafter be selected based onvarious factors such as channel quality, loading, interference, and soon. The terminal would then switch to the new downlink and/or uplinkchannel for communication. The frequency distance between the downlinkand uplink channels used by the terminal at any given moment may bedifferent from the nominal duplexing frequency.

In another embodiment, the base stations broadcast sector informationthat may be used by the terminals for communication, sector selection,and/or channel selection. The sector information may include varioustypes of information such as the downlink and uplink channels availablefor use, the frequencies of the available channels, the loading on theavailable channels, quality of service (QoS) information, and so on. Aterminal may receive sector information from one or more sectors. Theterminal may use the sector information to determine transmissionparameters for the downlink and/or uplink, e.g., the uplink channelfrequency. The terminal may also use the sector information to select asector, a downlink channel, and/or an uplink channel, possibly withouthaving to send any transmission on the uplink.

Various aspects and embodiments of the invention are described infurther detail below.

BRIEF DESCRIPTION OF THE DRAWINGS

Aspects of embodiments of the invention will become more apparent fromthe detailed description set forth below when taken in conjunction withthe drawings in which like reference characters identify correspondinglythroughout.

FIG. 1 shows a wireless communication system.

FIG. 2 shows an exemplary channel structure for an FDD system.

FIG. 3 shows an exemplary channel structure for a TDD system.

FIG. 4 shows an exemplary channel assignment for three-carrieroperation.

FIGS. 5 and 6 show a process and an apparatus, respectively, forcommunicating using configurable channels.

FIGS. 7 and 8 show a process and an apparatus, respectively, fordetermining frequency channels to use for communication.

FIGS. 9 and 10 show a process and an apparatus, respectively, forestablishing a connection with configurable channels.

FIG. 11 shows a block diagram of a base station and a terminal.

DETAILED DESCRIPTION

The word “exemplary” is used herein to mean “serving as an example,instance, or illustration.” Any embodiment or design described herein as“exemplary” is not necessarily to be construed as preferred oradvantageous over other embodiments or designs.

FIG. 1 shows a wireless communication system 100 with multiple basestations 110 and multiple terminals 120. A base station is a stationthat communicates with the terminals. A base station may also be called,and may contain some or all of the functionality of, a Node B, an accesspoint, and/or some other network entity. Each base station 110 providescommunication coverage for a particular geographic area 102. The term“cell” can refer to a base station and/or its coverage area depending onthe context in which the term is used. To improve system capacity, abase station coverage area may be partitioned into multiple smallerareas, e.g., three smaller areas 104 a, 104 b, and 104 c. Each smallerarea may be served by a respective base station sector (BSS), which mayalso be referred to as a base transceiver subsystem (BTS). The term“sector” can refer to a BSS and/or its coverage area depending on thecontext in which the term is used. For a sectorized cell, the BSSs forall sectors of that cell are typically co-located within the basestation for the cell. For simplicity, in the following description, theterm “base station” generically refers to a station that serves a cellas well as a station that serves a sector.

For a centralized architecture, a system controller 130 couples to basestations 110 and provides coordination and control for these basestations. System controller 130 may be a single network entity or acollection of network entities. System controller 130 may also becalled, and may contain some or all of the functionality of, a basestation controller (BSC), a mobile switching center (MSC), a radionetwork controller (RNC), and/or some other network entity. For adistributed architecture, the base stations may communicate with oneanother as needed.

Terminals 120 may be dispersed throughout the system, and each terminalmay be stationary or mobile. A terminal may also be called, and maycontain some or all of the functionality of, a wireless terminal (WT),an access terminal (AT), a mobile station (MS), a user equipment (UE), asubscriber station and/or some other entity. A terminal may be awireless device, a cellular phone, a personal digital assistant (PDA), awireless modem, a handheld device, and so on. A terminal may communicatewith one or more base stations on the downlink and uplink.

The transmission techniques described herein may be used for variouswireless communication systems and networks. The terms “system” and“network” are often used interchangeably. For example, the techniquesmay be used for wireless wide area networks (WWANs), wirelessmetropolitan area networks (WMANs), wireless local area networks(WLANs), and wireless personal area networks (WPANs).

The transmission techniques may also be used for various multiple-accessschemes such as Code Division Multiple Access (CDMA), Time DivisionMultiple Access (TDMA), Frequency Division Multiple Access (FDMA),Orthogonal FDMA (OFDMA), Single-Carrier FDMA (SC-FDMA), or a combinationthereof, e.g., OFDMA and CDMA. OFDMA and SC-FDMA partition a frequencychannel into multiple orthogonal tones, which are also calledsubcarriers, subbands, bins, and so on. Each tone may be modulated withdata. In general, modulation symbols are sent in the frequency domainwith OFDMA and in the time domain with SC-FDMA.

The transmission techniques may also be used for various radiotechnologies. For example, the techniques may be used for CDMA systemsthat implement cdma2000 and Wideband-CDMA (W-CDMA), TDMA systems thatimplement Global System for Mobile Communications (GSM), and OFDMAsystems that implement Flash-OFDM® from Flarion Technologies, IEEE802.11 a/g, IEEE 802.16, and IEEE 802.20. These various radiotechnologies are known in the art.

The techniques may also be used for FDD systems as well as time divisionduplexing (TDD) systems. An FDD system uses separate frequency channelsfor the downlink and uplink. A TDD system uses a single frequencychannel for both the downlink and uplink.

FIG. 2 shows an exemplary channel structure 200 that may be used in anFDD system. In structure 200, a frequency band includes a downlinkfrequency range and an uplink frequency range. The downlink frequencyrange is divided into multiple (K) downlink frequency channels (orsimply, downlink channels) with indices 0 through K−1. Similarly, theuplink frequency range is divided into multiple (K) uplink frequencychannels (or simply, uplink channels) with indices 0 through K−1. Eachfrequency channel has a particular bandwidth that is determined bysystem design. For example, a frequency channel may have a bandwidth of1.25 MHz in cdma2000 and Flash-OFDM®, 5 MHz in W-CDMA, 200 KHz in GSM,or 20 MHz in IEEE 802.11. Each frequency channel is centered at aspecific frequency that may be determined by a system operator orregulatory bodies. A frequency channel may also be referred to as aradio frequency (RF) channel, a carrier, a tone block, an OFDMA channel,a CDMA channel, and so on.

An FDD system typically uses fixed duplexing so that there is aone-to-one mapping between the downlink channels and the uplinkchannels. For example, downlink channel 0 may be associated with uplinkchannel 0, downlink channel 1 may be associated with uplink channel 1,and so on, and downlink channel K−1 may be associated with uplinkchannel K−1. With fixed duplexing, the use of a particular downlinkchannel also mandates the use of a specific uplink channel associatedwith this downlink channel.

FIG. 3 shows an exemplary channel structure 300 that may be used in aTDD system. The transmission timeline may be partitioned into frames,with each frame having a predetermined time duration. Each frame may bepartitioned into a downlink phase and an uplink phase. A base stationmay transmit data and signaling to terminals in the downlink phase, andthe terminals may transmit data and signaling to the base station in theuplink phase. Each phase may be partitioned into multiple time slots.Each time slot of the downlink phase may be considered as a downlinkchannel (DL Ch), and each time slot of the uplink phase may beconsidered as an uplink channel (UL Ch). The downlink and uplinkchannels correspond to different time intervals in a TDD system but maybe used in similar manner as the downlink and uplink channels in an FDDsystem.

The transmission techniques may be used for systems with sectorizedcells as well as systems with un-sectorized cells. For clarity, much ofthe description below is for an FDD system with sectorized cells. An FDDsystem typically has multiple pairs of downlink and uplink channelsavailable for use in a given geographic area. The available downlink anduplink channel pairs may be assigned to cells and sectors in the systemin various manners.

FIG. 4 shows an embodiment of a channel assignment scheme 400 forthree-carrier operation. For simplicity, FIG. 4 shows only three cellsA, B and C. Each cell x is partitioned into three sectors S_(x0), S_(x1)and S_(x2), for xε{A, B, C}. Sectors S_(x0), S_(x1), and S_(x2) may alsobe referred to as bssSectorType 0, 1 and 2, respectively.

In the embodiment shown in FIG. 4, the system has three downlinkchannels that are denoted as F₀, F₁ and F₂ and three uplink channelsthat are denoted as U₀, U₁ and U₂. On clarity, only the downlinkchannels are shown in FIG. 4. The three frequency channels for each linkmay be contiguous and separated by a predetermined frequency distancethat is known to the sectors and the terminals. The three frequencychannels for each link may also be non-contiguous and separated bynon-standard frequency distances.

In channel assignment scheme 400, all three downlink and uplink channelpairs are assigned to each sector. For each sector, one downlink channelis designated as a primary downlink channel, and the other two downlinkchannels are designated as auxiliary downlink channels 1 and 2.Similarly, for each sector, one uplink channel is designated as aprimary uplink channel, and the other two uplink channels are designatedas auxiliary uplink channels 1 and 2. Different sectors have differentprimary downlink and uplink channels. In particular, channels F₀ and U₀are respectively the primary downlink and uplink channels for sectorS_(x0), channels F₁ and U₁ are respectively the primary downlink anduplink channels for sector S_(x1), and channels F₂ and U₂ arerespectively the primary downlink and uplink channels for sector S_(x2).For each sector, FIG. 4 shows the primary downlink channel in boldedtext and the auxiliary downlink channels within parentheses. The uplinkchannels are not shown in FIG. 4 for simplicity. Table 1 gives theprimary and auxiliary frequency channels for each sector.

TABLE 1 Sector S_(x0) Sector S_(x1) Sector S_(x2) Primary channels F₀and U₀ F₁ and U₁ F₂ and U₂ Auxiliary channels 1 F₁ and U₁ F₂ and U₂ F₀and U₀ Auxiliary channels 2 F₂ and U₂ F₀ and U₀ F₁ and U₁

In an OFDMA system, a set of tones may be defined for each frequencychannel and may be referred to as a tone block. Three tone blocks 0, 1and 2 may be defined for downlink channels F₀, F₁ and F₂, and three toneblocks may be defined for uplink channels U₀, U₁ and U₂. The tone blockfor the primary frequency channel may be referred to as tier 0 toneblock. The tone blocks for auxiliary frequency channels 1 and 2 may bereferred to as tier 1 tone block and tier 2 tone block, respectively.Table 2 gives the tone blocks for each sector and is equivalent to Table1.

TABLE 2 bssSectorType = 0 bssSectorType = 1 bssSectorType = 2 Tier 0Tone block 0 Tone block 1 Tone block 2 tone block Tier 1 Tone block 1Tone block 2 Tone block 0 tone block Tier 2 Tone block 2 Tone block 0Tone block 1 tone block

Each sector may serve the terminals in that sector using the assignedfrequency channels/tone blocks. If the system uses fixed duplexing, thena terminal communicating with a sector on downlink channel F₀ would alsouse uplink channel U₀, a terminal communicating with a sector ondownlink channel F₁ would also use uplink channel U₁, and a terminalcommunicating with a sector on downlink channel F₂ would also use uplinkchannel U₂. The fixed duplexing may simplify system operation but mayresult in sub-optimal performance. For example, a terminal usingdownlink channel F₀ may find uplink channel U₀ congested or may observehigh level of interference on uplink channel U₀. However, the fixedduplexing would require the terminal to use uplink channel U₀, unlessthe terminal selects a different pair of downlink and uplink channels,if available.

In an aspect, configurable downlink and/or uplink channels are used fora terminal to improve performance. In general, a system may support onlyconfigurable downlink channels (e.g., for a deployment with multipledownlink channels and a single uplink channel), only configurable uplinkchannels (e.g., for a deployment with multiple uplink channels and asingle downlink channel), or configurable downlink and uplink channels.With configurable channels, a suitable downlink channel and/or asuitable uplink channel may be selected for a terminal to achieve goodperformance. The use of configurable channels may result in variableduplexing and may be viewed as a form of dynamic frequency reuse (DFR).

In an embodiment, a terminal initially establishes a connection with asector on default downlink and uplink channels, which may also bereferred to as preferred or designated channels. A connection may beconsidered as a collection of channels established between the terminaland the sector for the physical (PHY) and/or Medium Access Control (MAC)layers. The default downlink and uplink channels may be provisioned atthe terminal and may result from licensed or unlicensed spectrumallocation and/or spectrum planning. For example, the default downlinkand uplink channels may be the primary downlink and uplink channels,which may be different for different sectors as shown in FIG. 4. Theterminal may thereafter switch to another downlink channel and/oranother uplink channel, which may be selected based on various factorsas described below.

The selection of a new downlink channel and/or a new uplink channel maybe made by the sector or the terminal. In an embodiment, the sectorselects a new downlink channel and/or a new uplink channel for theterminal and sends a message for a change to the new channel(s). Themessage may be a directive that is followed by the terminal or a requestthat may be accepted or rejected by the terminal. The sector may sendthe message on a control channel, a traffic channel, or a broadcastchannel. In another embodiment, the terminal may make measurements fordifferent downlink channels and/or obtain information for differentuplink channels. The terminal may select a new downlink channel and/or anew uplink channel based on the measurements and/or information. Theterminal may send a message for a change to the new channel(s). For bothembodiments, the change to the new channel(s) may occur at a designatedtime that is known to both the sector and the terminal.

At the designated time, the terminal tunes to the new downlink channeland/or the new uplink channel and thereafter uses these channels forcommunication with the sector. After RF tuning takes effect, thefrequency distance between the downlink and uplink channels may bedifferent from the frequency distance between the default downlink anduplink channels. The variable duplexing may be achieved with appropriateRF circuitry such as duplexers, filters, and local oscillators in the RFtransmit and receive chains. The RF tuning may be performed relativelyquickly (e.g., in milliseconds) with RF circuitry currently available.Hence, data connectivity at higher layers may be maintained throughchannel switching, and impact to user applications may be minimal.

In general, the selection of new downlink and/or uplink channels may bemade based on various factors such as channel quality, loading,interference, and so on. The channel selection may consider channelqualities of the frequency channels. Different frequency channels mayobserve different channel conditions, e.g., different fading, multipath,and interference effects. Consequently, these frequency channels mayhave different channel qualities, which may be quantified bysignal-to-noise ratio (SNR) or some other measure. A terminal mayestimate the channel qualities of different downlink channels based onpilots and/or other transmissions sent by a sector. The sector may alsoestimate the channel qualities of the uplink channels based ontransmissions from the terminal. Downlink and uplink channels with goodchannel qualities may be selected for use.

The channel selection may take into account loading, which refers to theamount of traffic being sent, e.g., on a frequency channel of a sector.Loading may be quantified by the number of users or connections, the QoSprofiles of these users, and/or other criteria. A QoS profile may conveythe type(s) of traffic being sent and the traffic requirements. Thechannel selection may be performed in a manner to balance loading acrossfrequency channels, across sectors, and/or across cells.

It is desirable to balance the loading of different frequency channelsof a given sector. This may be achieved by determining the loading ofeach frequency channel on each link. For each link, new connections maybe established on frequency channels with less loading and/or existingconnections may be moved to more lightly loaded frequency channels.

It is also desirable to balance the loads of different sectors of agiven cell and also across adjacent cells. If a terminal is located nearthe coverage edge of two sectors, then the terminal may switch from one(more heavily loaded) frequency channel of one sector to another (morelightly loaded) frequency channel of another sector. Similarly, if theterminal is located near the coverage edge of two cells, then theterminal may switch from one (more heavily loaded) frequency channel ofone cell to another (more lightly loaded) frequency channel of anothercell. Load balancing across sectors or cells may be achieved, e.g., byexchanging pertinent information on the available frequency channels,the number of users, the QoS profiles of the users, and/or otherinformation among the sectors or cells. Information may be exchangedamong sectors of a given cell via a backplane of a base station.Information may be exchanged among cells via backhaul networks.

In general, load balancing may be performed across frequency channels ofa sector, across sectors of a cell, and/or across cells. Dynamic loadbalancing may improve QoS for all users. Load balancing may be performedby the sectors and/or the terminals. A sector typically has informationon the users and their QoS profiles and further controls usage of radioresources on the downlink and uplink. A sector may request changes indownlink and/or uplink channels for terminals in order to balanceloading. A sector may also broadcast loading information. The terminalsmay then consider the loading information in selecting downlink and/oruplink channels.

The channel selection may be performed in a manner to mitigateinter-sector interference and inter-cell interference. Transmissions forterminals in one sector (or cell) are typically not orthogonal totransmissions for terminals in other sectors (or cells) and thus causeinter-sector (or inter-cell) interference. If a terminal is located inthe boundary of two sectors, then the terminal may be assigned downlinkand uplink channels that reduce the impact of inter-sector interference.For example, in FIG. 4, a sector-edge terminal T_(A) in sector S_(B1)may be assigned downlink channel F₁. Adjacent sector S_(B2) may usedownlink channel F₁ for interior terminals that can tolerate moreinterference. Terminal T_(A) may also be restricted to transmitting toone sector to reduce inter-sector interference. Similarly, if a terminalis located in the boundary of multiple cells, then the terminal may beassigned downlink and uplink channels that reduce the impact ofinter-cell interference. For example, in FIG. 4, a cell-edge terminal TBin sector S_(B1) may be assigned downlink channel F₁, which is anauxiliary channel for adjacent cells A and C. Cells A and C may usedownlink channel F₁ for interior terminals that can tolerate moreinterference. The sectors or cells may exchange information on thefrequency channels used by each sector or cell, the interferenceobserved on each frequency channel, the types of terminal assigned oneach frequency channel, and so on. This information may be used byneighbor sectors or cells to assign frequency channels in a manner tomitigate the impact of inter-sector and inter-cell interference.

The channel selection may also take into consideration interference fromother sources that may degrade the transmissions between the sectors andterminals. This interference may come from other radio technologies(e.g., near borders between regions with different spectrum policies),rogue transmitters, and so on. If high interference is observed on agiven frequency channel, then another frequency channel may be selectedfor use.

The channel selection may also take into consideration other factorsbesides those described above.

A new downlink channel and/or a new uplink channel may be selectedwhenever appropriate. For example, a terminal may periodically measurethe received powers or estimate the channel qualities of other downlinkchannels for a serving sector and/or search for better downlink channelsof other sectors. A new downlink channel of the serving sector oranother sector may be selected if better than the current downlinkchannel.

The selection of new downlink and/or uplink channels may be conveyedusing various mechanisms. A sector may send channel changes in broadcastcontrol messages to all terminals, multicast control messages to groupsof terminals, and/or unicast control messages to specific terminals. Aterminal may send channel changes in unicast control messages. Ingeneral, the messages may be sent on broadcast, control, and/or trafficchannels.

Configurable channels may be implemented on a per sector basis, andchannel selection may be performed independently by each sector.Configurable channels may also be implemented on a per cell basis, andchannel selection may be performed independently by each cell.Configurable channels may also be implemented across a group of sectorsor cells. In any case, configurable channels may be implemented in amanner to observe any applicable regulatory or co-existencerestrictions.

FIG. 5 shows an embodiment of a process 500 for communicating usingconfigurable channels. Process 500 may be performed by a terminal or abase station.

A connection between the terminal and the base station is establishedvia a first frequency channel for a first link and a second frequencychannel for a second link (block 512). A selection of a third frequencychannel for the first link is obtained (block 514). The connection isswitched to the third frequency channel for the first link (block 516).The connection is maintained with the second frequency channel for thesecond link after switching to the third frequency channel for the firstlink. The first and second frequency channels have a first frequencydistance that is different than a second frequency distance between thesecond and third frequency channels. This difference may be at least thespacing between adjacent frequency channels for the first link or thesecond link.

The first and second links may be the downlink and uplink, respectively,and the first and second frequency channels may be default frequencychannels for the downlink and uplink, respectively. The third frequencychannel may be selected from a set of downlink frequency channelsavailable for the base station. Alternatively, the first and secondlinks may be the uplink and downlink, respectively, and the first andsecond frequency channels may be default frequency channels for theuplink and downlink, respectively. The third frequency channel may beselected from a set of uplink frequency channels available for the basestation.

The third frequency channel may be selected in response to (1) lessloading detected on the third frequency channel than the first frequencychannel, (2) less interference detected on the third frequency channelthan the first frequency channel, (3) better channel conditions detectedon the third frequency channel than the first frequency channel, and/or(4) some other factors. The selection of the third frequency channel maybe made by the base station and sent to the terminal or made by theterminal and sent to the base station.

A selection of a fourth frequency channel for the second link may beobtained (block 518). The connection may then be switched to the fourthfrequency channel for the second link (block 520). The third and fourthfrequency channels may have a third frequency distance that is differentthan the first and second frequency distances.

FIG. 6 shows an embodiment of an apparatus 600 for communicating usingconfigurable channels. Apparatus 600 includes means for establishing aconnection between a terminal and a base station via a first frequencychannel for a first link and a second frequency channel for a secondlink (block 612), means for obtaining a selection of a third frequencychannel for the first link (block 614), means for switching theconnection to the third frequency channel for the first link (block616), means for obtaining a selection of a fourth frequency channel forthe second link (block 618), and means for switching the connection tothe fourth frequency channel for the second link (block 620).

In another aspect, the sectors broadcast sector information that may beused by the terminals for proper operation, sector selection, and/orchannel selection. The sector information may also be called carrier BSSinformation, carrier BS information, carrier information, and so on.Each sector may broadcast its sector information on only the primarydownlink channel or on each downlink channel. A terminal may receivesector information from one or more sectors, e.g., strongly receivedsector(s). The terminal may use the sector information to select asector, a downlink channel, and/or an uplink channel. The terminal maybe able to perform sector and/or channel selection without having tosend any transmission on the uplink.

In general, the sector information may comprise any type of informationthat may be pertinent for proper operation, sector selection, and/orchannel selection. For example, the sector information may indicatewhich frequency channels are the primary and auxiliary channels, whichdownlink and uplink channels are available for use, the frequencydistances between the downlink channels, the frequency distances betweenthe uplink channels, the frequency distances between the downlink anduplink channels, the loading on each uplink channel, the loading on eachdownlink channel, a power backoff for each auxiliary channel, QoSinformation for each channel, and so on, or any combination thereof. Thesector information may be conveyed in various manners.

In an embodiment, each sector transmits a known signal on each downlinkchannel. The known signal may be used for sector detection andidentification and may be a beacon, a known sequence, a pilot, or someother signal. A beacon is a high-power transmission sent on a specificfrequency or tone. Each sector may transmit beacons on three downlinkchannels in a manner such that the terminals can identify the primarychannel as well as auxiliary channels 1 and 2 based on the beacons. Forexample, sector S_(x0) may transmit beacons on tone blocks 0, 1 and 2 insuperslots (or time intervals) 0, 1 and 2, respectively, sector S_(x1)may transmit beacons on tone blocks 1, 2 and 0 in superslots 0, 1 and 2,respectively, and sector S_(x2) may transmit beacons on tone blocks 2, 0and 1 in superslots 0, 1 and 2, respectively. In this embodiment, theterminals are able to determine the primary and auxiliary channels ofeach sector based on the beacons received from that sector.

Each sector has a set of downlink channels available for use and a setof uplink channels available for use. In an embodiment, the availabledownlink channels are independent of the available uplink channels. Forexample, one sector may use three downlink channels and two uplinkchannels, another sector may use two downlink channels and three uplinkchannels, and so on. The number of available frequency channels for eachlink may be selected based on various factors such as sector loading,interference, and so on. In another embodiment, the available downlinkchannels are tied to the available uplink channels. For example, onesector may use only the primary downlink and uplink channels, anothersector may use the primary downlink and uplink channels as well asauxiliary downlink and uplink channels 1, and another sector may use allthree downlink and uplink channel pairs.

In an embodiment, each sector uses the primary downlink and uplinkchannels and may or may not use the auxiliary downlink and uplinkchannels. Table 3 lists four possible configurations for a sector. Eachconfiguration corresponds to a different set of frequency channel(s)used by a sector.

TABLE 3 bssToneBlock bssToneBlock bssToneBlock bssToneBlock Config = 0Config = 1 Config = 2 Config = 3 Tier 0 tone block Used Used Used UsedTier 1 tone block Used Not used Used Not used Tier 2 tone block UsedUsed Not used Not used

The sector information may convey the downlink channels and/or theuplink channels available for use. The sector information may conveyboth the available downlink channels and the available uplink channels,if these channels may be selected independently of one another. Thesector information may also convey only the available downlink channels,e.g., if the downlink and uplink channels are selected in pairs. Thesector information may also indicate a specific downlink channel and/ora specific uplink channel to use.

In an embodiment, the frequency channels available for use are conveyedby power backoffs for the auxiliary channels. The power backoff for agiven auxiliary channel is a power ratio of the nominal (e.g., per-tone)transmission power used for the primary channel to the nominaltransmission power used for that auxiliary channel. A power backoff of 0decibel (dB) indicates that the same transmission power can be used forthe primary and auxiliary channels, a power backoff of more than 0 dBindicates that less transmission power can be used for the auxiliarychannel than the primary channel, and a power backoff of infinityindicates that the auxiliary channel cannot be used. Table 4 gives theconfiguration of a sector based on the power backoffs for the auxiliarychannels. In Table 4, bssPowerBackoff01 is the power backoff forauxiliary channel 1, and bssPowerBackoff02 is the power backoff forauxiliary channel 2.

TABLE 4 bssPowerBackoff01 bssPowerBackoff02 bssToneBlockConfig Not equalto infinity Not equal to infinity dB 0 dB Equal to infinity dB Not equalto infinity dB 1 Not equal to infinity Equal to infinity dB 2 dB Equalto infinity dB Equal to infinity dB 3

The sector information may convey an uplink (UL) loading factor for eachof the uplink channels supported by a sector. The UL loading factor fora given uplink channel indicates the amount of loading on that uplinkchannel at the sector. The UL loading factor may be given by a rise overthermal (ROT), an interference over thermal (IOT), and/or some othermeasure known in the art. The terminals can ascertain the loading on agiven uplink channel based on the UL loading factor for that uplinkchannel.

The sector information may convey loading information for downlinkchannels supported by a sector. The loading information for the downlinkmay be given in the same or different format than the loadinginformation for the uplink channels. The sector information may alsoindicate which downlink channels are available for use in the sector aswell as the power backoff for each available downlink channel.

The sector information may convey the frequency distances between thedownlink channels and/or the frequency distances between the uplinkchannels, if these frequency channels are not contiguous. The downlinkand uplink channels may be symmetrical so that the frequency distancebetween auxiliary downlink channel y and the primary downlink channel isequal to the frequency distance between auxiliary uplink channel y andthe primary uplink channel, for y=1, 2. In this case, the frequencydistances for the downlink channels also apply to the uplink channels.The frequency distance between auxiliary channel 1 and the primarychannel may be denoted as FrequencyOffset10, and the frequency distancebetween auxiliary channel 2 and the primary channel may be denoted asFrequencyOffset10. The frequency distance may be given in apredetermined unit (e.g., the spacing between adjacent tones in a toneblock). If the downlink and uplink channels are not symmetrical, thenthe sector information may include the frequency distances for thedownlink channels as well as the frequency distances for the uplinkchannels. In any case, the frequency distances may be used to find theauxiliary channels.

The sector information may convey the center frequencies of the uplinkchannels. In a typical system deployment, each downlink channel has acorresponding uplink channel that is located at a fixed frequencydistance away. In this case, the frequencies of the uplink channels maybe determined based on the frequencies of the downlink channels.However, a system deployment may have uplink channels that are notseparated from the corresponding downlink channels by the fixedfrequency distance. In this case, the sector information may convey thecenter frequencies of the uplink channels. The terminals can ascertainthe locations of the uplink channels based on the sector information.

The sector information may also convey QoS information for the downlinkand/or uplink channels. The system may support multiple priority levels,e.g., high, normal, and low priority. The QoS information for a givenfrequency channel may indicate, e.g., the number of users in eachpriority level, the amount of traffic in each priority level, theminimum priority level needed to access the frequency channel, and soon. A terminal may select a frequency channel with less traffic athigher priority levels so that the terminal can be adequately served.

Table 5 shows an embodiment of the sector information that is broadcastby a sector. The sector information may also comprise differentcombination of information, and this is within the scope of the presentinvention.

TABLE 5 Parameter Description FrequencyOffset10 Frequency distancebetween auxiliary channel 1 and primary channel FrequencyOffset20Frequency distance between auxiliary channel 2 and primary channelbssPowerBackoff01 Transmission power backoff for auxiliary channel 1bssPowerBackoff02 Transmission power backoff for auxiliary channel 2 ULloading factor 0 Loading factor for primary uplink channel UL loadingfactor 1 Loading factor for auxiliary uplink channel 1 UL loading factor2 Loading factor for auxiliary uplink channel 2

A terminal may estimate the channel qualities of the downlink channelsof one or more sectors that can be received by the terminal. Theterminal may select a sector, e.g., the sector with the strongestdownlink channel, and may obtain sector information from the selectedsector. The terminal may use the sector information in various manners.In an embodiment, the sector information conveys the frequencies of theuplink channels, which are not at fixed distance from the correspondingdownlink channels. The terminal may then transmit on an uplink channelat the frequency indicated by the sector information. In anotherembodiment, the sector information conveys loading, QoS, and/or otherinformation for the uplink channels. The terminal may then select anuplink channel based on the sector information.

The UL loading factors broadcast by a sector may be used to balance theloads on the uplink channels. In an embodiment, when a terminal firstaccesses a sector, the UL loading factors of the primary and auxiliaryuplink channels are obtained from the sector and used to select anuplink channel, e.g., the uplink channel with the lightest load. Inanother embodiment, if the loading of the current uplink channel exceedsthe loading of another uplink channel by a predetermined amount, then aswitch is made to the more lightly loaded uplink channel.

The sector information may be used to select a sector, a downlinkchannel, and/or an uplink channel at the start of communication. Aconnection may be established with the selected sector on the selecteddownlink and uplink channels. The sector information may also be used to(1) switch the existing connection to a new downlink channel and/or anew uplink channel of the current sector, or (2) add a new connection ona new downlink channel and/or a new uplink channel with the currentsector (e.g., for additional traffic) or another sector (e.g., forhandoff).

FIG. 7 shows an embodiment of a process 700 for determining frequencychannels to use for communication. Process 700 may be performed by aterminal. The terminal tunes to a downlink channel, which may bedetected based on beacons or pilots transmitted on the downlink (block712). The terminal receives sector information sent (e.g., broadcast) bya base station on the downlink channel (block 714). The terminalascertains an uplink channel based on the sector information (block716). The terminal then uses the uplink channel for communication withthe base station (block 718).

The sector information may indicate a specific uplink channel to use forcommunication, and the terminal may then use this uplink channel. Thesector information may indicate the center frequency of the uplinkchannel, and the terminal may tune its transmitter to this centerfrequency. The sector information may indicate multiple uplink channelsavailable for use and may further indicate loading, QoS, and/or otherinformation for these uplink channels. The terminal may then select theuplink channel by considering the loading, QoS, and/or other informationfor the uplink channels. The terminal may also use the sectorinformation in other manners for the uplink.

The sector information may include information (e.g., centerfrequencies) for additional downlink channels. The terminal may acquireeach additional downlink channel and determine the channel conditions ofeach downlink channel. The terminal may select one downlink for use fromamong all available downlink channels.

The terminal may send an access request on the selected uplink channelto the base station. The terminal may also establish a connection withthe base station via the selected downlink and uplink channels.

FIG. 8 shows an embodiment of an apparatus 800 for determining frequencychannels to use for communication. Apparatus 800 includes means fortuning to a downlink channel (block 812), means for receiving sectorinformation sent by a base station on the downlink channel (block 814),means for ascertaining an uplink channel based on the sector information(block 816), and means for using the uplink channel for communicationwith the base station (block 818).

The transmission techniques and configurable channels described hereinmay provide certain advantages. Improved QoS and/or reduced interferencemay be achieved by selecting appropriate downlink and/or uplink channelsfor use. This may result in enhanced coverage, capacity and/orperformance for the system.

FIG. 9 shows an embodiment of a process 900 for establishing aconnection with configurable channels. A first frequency channel isselected from among at least one frequency channel for a first link,e.g., the downlink (block 912). The first frequency channel may beselected based on measurements for the frequency channel(s) for thefirst link, sector information received from one of the frequencychannel(s), and/or some other information. A second frequency channel isselected from among multiple frequency channels for a second link, e.g.,the uplink (block 914). The second frequency channel may be selectedbased on the sector information and/or some other information. Aconnection is established via the first frequency channel for the firstlink and the second frequency channel for the second link (block 916).

The multiple frequency channels for the second link may be associatedwith the frequency channel(s) for the first link. The multiple frequencychannels for the second link may include the second frequency channeland a third frequency channel, where the frequency distance between thefirst and second frequency channels and the frequency distance betweenthe first and third frequency channels are different by at least thespacing between adjacent frequency channels for the second link.

FIG. 10 shows an embodiment of an apparatus 1000 for establishing aconnection with configurable channels. Apparatus 1000 includes means forselecting a first frequency channel from among at least one frequencychannel for a first link (block 1012), means for selecting a secondfrequency channel from among multiple frequency channels for a secondlink (block 1014), and means for establishing a connection via the firstfrequency channel for the first link and the second frequency channelfor the second link (block 1016).

FIG. 11 shows a block diagram of an embodiment of a base station 110 anda terminal 120 in FIG. 1. At base station 110, a transmit (TX) data andsignaling processor 1110 receives traffic data for the terminals beingserved, signaling (e.g., messages to switch channels), and overhead data(e.g., sector information) for each downlink channel. Processor 1110processes (e.g., formats, encodes, interleaves, and symbol maps) thetraffic data, signaling, overhead data, and pilot for each downlinkchannel and provides output symbols for the downlink channel. Amodulator 1112 performs modulation on the output symbols for eachdownlink channel and generates chips. Modulator 1112 may performmodulation for OFDM, CDMA, and/or other radio technologies. Atransmitter (TMTR) 1114 conditions (e.g., converts to analog, filters,amplifies, and upconverts) the chips and generates a downlink signalcontaining a modulated signal component for each downlink channel. Thedownlink signal is transmitted via an antenna 1116.

At terminal 120, an antenna 1152 receives downlink signals from basestation 110 and other base stations and provides a received signal to areceiver (RCVR) 1154. Receiver 1154 conditions and digitizes thereceived signal and provides samples. A demodulator (Demod) 1156performs demodulation on the samples for each downlink channel ofinterest and provides symbol estimates for the downlink channel. Areceive (RX) data and signaling processor 1158 processes (e.g., symboldemaps, deinterleaves, and decodes) the symbol estimates for thedownlink channel assigned to terminal 120 and provides decoded data andsignaling for terminal 120. Processor 1158 may also process the symbolestimates to obtain decoded overhead data, e.g., sector information.Demodulator 1156 and RX data and signaling processor 1158 performprocessing complementary to the processing performed by modulator 1112and TX data and signaling processor 1110, respectively.

For the uplink, a TX data and signaling processor 1160 generates outputsymbols for traffic data, signaling, and pilot to be sent to basestation 110. A modulator 1162 performs modulation on the output symbolsand generates chips. A transmitter 1164 conditions the chips andgenerates an uplink signal for the uplink channel assigned to terminal120. The uplink signal is transmitted via antenna 1152.

At base station 110, the uplink signals from terminal 120 and otherterminals are received by antenna 1116, conditioned and digitized by areceiver 1120, demodulated by a demodulator 1122, and processed by an RXdata and signaling processor 1124 to recover the traffic data andsignaling sent by terminal 120 and other terminals.

Controllers/processors 1130 and 1170 direct the operation of variousprocessing units at base station 110 and terminal 120, respectively.Controller/processor 1130 may perform process 500 in FIG. 5 and/or otherprocesses. Controller/processor 1170 may perform process 500 in FIG. 5,process 700 in FIG. 7, process 900 in FIG. 9, and/or other processes.Controller/processor 1170 may receive messages and sector informationfrom processor 1158 and may perform various functions. For example,controller/processor 1170 may determine transmission parameters (e.g.,uplink channel frequency) for terminal 120, select downlink and/oruplink channels, and/or determine whether to switch downlink and/oruplink channels. Memories 1132 and 1172 store program codes and data forbase station 10 and terminal 120, respectively.

Local oscillator (LO) generators 1134 and 1174 generate LO signals atthe proper frequencies for frequency upconversion by transmitters 1114and 1164, respectively. LO generators 1134 and 1174 also generate LOsignals at the proper frequencies for frequency downconversion byreceivers 1120 and 1154, respectively. Transmitters 1114 and 1164 andreceivers 1120 and 1154 include suitable RF circuitry (e.g., duplexers,filters, and so on) to support downlink and uplink channels at differentfrequencies.

The transmission techniques described herein may be implemented byvarious means. For example, these techniques may be implemented inhardware, firmware, software, or a combination thereof. For a hardwareimplementation, the processing units at a terminal or a base station maybe implemented within one or more application specific integratedcircuits (ASICs), digital signal processors (DSPs), digital signalprocessing devices (DSPDs), programmable logic devices (PLDs), fieldprogrammable gate arrays (FPGAs), processors, controllers,micro-controllers, microprocessors, electronic devices, other electronicunits designed to perform the functions described herein, or acombination thereof.

For a firmware and/or software implementation, the transmissiontechniques may be implemented with modules (e.g., procedures, functions,and so on) that perform the functions described herein. The firmwareand/or software codes may be stored in a memory (e.g., memory 1132 or1172 in FIG. 11) and executed by a processor (e.g., processor 1130 or1170). The memory may be implemented within the processor or external tothe processor.

The previous description of the disclosed embodiments is provided toenable any person skilled in the art to make or use the presentinvention. Various modifications to these embodiments will be readilyapparent to those skilled in the art, and the generic principles definedherein may be applied to other embodiments without departing from thespirit or scope of the invention. Thus, the present invention is notintended to be limited to the embodiments shown herein but is to beaccorded the widest scope consistent with the principles and novelfeatures disclosed herein.

What is claimed is:
 1. An apparatus comprising: at least one processorconfigured to establish a connection between a terminal and a currentsector serving the terminal via a first frequency channel for a firstlink and a second frequency channel for a second link for utilizingfrequency division duplexing, to select a third frequency channel frommultiple frequency channels available in the current sector for thefirst link based at least in part on frequency distances between themultiple frequency channels available in the current sector for thefirst link, wherein the first frequency channel and the third frequencychannel are in the same frequency band, and to switch the connectionbetween the terminal and the current sector to the third frequencychannel for the first link while continuing to utilize frequencydivision duplexing and maintaining the connection between the terminaland the current sector via the second frequency channel for the secondlink, wherein the first, second, and third frequency channels aredifferent from one another, and wherein the first and second frequencychannels have a first frequency distance that is different than a secondfrequency distance between the second and third frequency channels; anda memory coupled to the at least one processor.
 2. The apparatus ofclaim 1, wherein the first frequency distance is different than thesecond frequency distance by at least a spacing between adjacentfrequency channels for the first link or the second link.
 3. Theapparatus of claim 1, wherein the at least one processor is configuredto select a fourth frequency channel from multiple frequency channelsavailable in the current sector for the second link based on frequencydistances between the multiple frequency channels available in thecurrent sector for the second link and to switch the connection betweenthe terminal and the current sector to the fourth frequency channel forthe second link, wherein the third and fourth frequency channels have athird frequency distance that is different than at least one of thefirst or second frequency distances, wherein the second frequencychannel and the fourth frequency channel are in the same frequency bandas the first frequency channel and the third frequency channel.
 4. Theapparatus of claim 1, wherein the first and second links are downlinkand uplink, respectively, and wherein the first and second frequencychannels are default frequency channels for the downlink and uplink,respectively.
 5. The apparatus of claim 4, wherein the multiplefrequency channels available in the current sector for the first linkcomprise a set of downlink frequency channels available for use in thecurrent sector.
 6. The apparatus of claim 1, wherein the first andsecond links are uplink and downlink, respectively, and wherein thefirst and second frequency channels are default frequency channels forthe uplink and downlink, respectively.
 7. The apparatus of claim 6,wherein the multiple frequency channels available in the current sectorfor the first link comprise a set of uplink frequency channels availablefor use in the current sector.
 8. The apparatus of claim 1, wherein theat least one processor is further configured to select the thirdfrequency channel based on the third frequency channel having lessloading than the first frequency channel.
 9. The apparatus of claim 1,wherein the at least one processor is further configured to select thethird frequency channel based on the third frequency channel having lessinterference than the first frequency channel.
 10. The apparatus ofclaim 1, wherein the at least one processor is further configured toselect the third frequency channel based on the third frequency channelhaving better channel conditions than the first frequency channel. 11.The apparatus of claim 1, wherein the at least one processor isconfigured to establish the connection between the terminal and a basestation that serves the current sector and to receive one or more ofsector information associated with the multiple frequency channelsavailable in the current sector or the selection of the third frequencychannel from the base station.
 12. The apparatus of claim 1, wherein theat least one processor is configured to establish the connection betweenthe terminal and a base station that serves the current sector and tosend one or more of sector information associated with the multiplefrequency channels available in the current sector or the selection ofthe third frequency channel to the terminal.
 13. A method comprising:establishing a connection between a terminal and a current sectorserving the terminal via a first frequency channel for a first link anda second frequency channel for a second link for utilizing frequencydivision duplexing; selecting a third frequency channel from multiplefrequency channels available in the current sector for the first linkbased at least in part on frequency distances between the multiplefrequency channels available in the current sector for the first link,wherein the first frequency channel and the third frequency channel arein the same frequency band; and switching the connection between theterminal and the current sector to the third frequency channel for thefirst link while continuing to utilize frequency division duplexing andmaintaining the connection between the terminal and the current sectorvia the second frequency channel for the second link, wherein the first,second, and third frequency channels are different from one another, andwherein the first and second frequency channels have a first frequencydistance that is different than a second frequency distance between thesecond and third frequency channels.
 14. The method of claim 13, whereinselecting the third frequency channel comprises: determining loading onthe third frequency channel from sector information associated with themultiple frequency channels available in the current sector for thefirst link; and selecting the third frequency channel based further onthe sector information indicating that the third frequency channel hasless loading than the first frequency channel.
 15. The method of claim13, wherein selecting the third frequency channel comprises: determininginterference on the third frequency channel from sector informationassociated with the multiple frequency channels available in the currentsector for the first link; and selecting the third frequency channelbased further on the sector information indicating that the thirdfrequency channel has less interference than the first frequencychannel.
 16. An apparatus comprising: means for establishing aconnection between a terminal and a current sector serving the terminalvia a first frequency channel for a first link and a second frequencychannel for a second link for utilizing frequency division duplexing;means for selecting a third frequency channel from multiple frequencychannels available in the current sector for the first link based atleast in part on frequency distances between the multiple frequencychannels available in the current sector for the first link, wherein thefirst frequency channel and the third frequency channel are in the samefrequency band; and means for switching the connection between theterminal and the current sector to the third frequency channel for thefirst link while continuing to utilize frequency division duplexing andmaintaining the connection between the terminal and the current sectorvia the second frequency channel for the second link, wherein the first,second, and third frequency channels are different from one another, andwherein the first and second frequency channels have a first frequencydistance that is different than a second frequency distance between thesecond and third frequency channels.
 17. The apparatus of claim 16,wherein the means for selecting the third frequency channel comprises:means for determining loading on the third frequency channel from sectorinformation associated with the multiple frequency channels available inthe current sector for the first link; and means for selecting the thirdfrequency channel based further on the sector information indicatingthat the third frequency channel has less loading than the firstfrequency channel.
 18. The apparatus of claim 16, wherein the means forselecting the third frequency channel comprises: means for determininginterference on the third frequency channel from sector informationassociated with the multiple frequency channels available in the currentsector for the first link; and means for selecting the third frequencychannel based further on the sector information indicating that thethird frequency channel has less interference than the first frequencychannel.
 19. A non-transitory computer-readable medium includinginstructions stored thereon, comprising: a first instruction set forestablishing a connection between a terminal and a current sectorserving the terminal via a first frequency channel for a first link anda second frequency channel for a second link for utilizing frequencydivision duplexing; a second instruction set for selecting a thirdfrequency channel from multiple frequency channels available in thecurrent sector for the first link based at least in part on frequencydistances between the multiple frequency channels available in thecurrent sector for the first link, wherein the first frequency channeland the third frequency channel are in the same frequency band; and athird instruction set for switching the connection between the terminaland the current sector to the third frequency channel for the first linkwhile continuing to utilize frequency division duplexing and maintainingthe connection between the terminal and the current sector via thesecond frequency channel for the second link, wherein the first, second,and third frequency channels are different from one another, and whereinthe first and second frequency channels have a first frequency distancethat is different than a second frequency distance between the secondand third frequency channels.
 20. A terminal comprising: at least oneprocessor configured to receive sector information sent by a basestation on a downlink channel, to ascertain an uplink channel based onthe sector information, and to use the uplink channel for communicationwith the base station, wherein the sector information indicates multipleuplink channels and multiple downlink channels available for use withthe base station that sent the sector information, wherein the multipleavailable uplink channels and the multiple available downlink channelsare in the same frequency band, and wherein the at least one processoris further configured to ascertain the uplink channel based on frequencydistances between at least one of the multiple uplink channels or themultiple downlink channels available for use with the base station thatsent the sector information; and a memory coupled to the at least oneprocessor.
 21. The terminal of claim 20, wherein the at least oneprocessor is configured to ascertain center frequency of the uplinkchannel based on the frequency distances and to tune a transmitter tothe center frequency of the uplink channel.
 22. The terminal of claim20, wherein the sector information indicates a specific uplink channelto use for communication, and wherein the ascertained uplink channel isthe specific uplink channel indicated by the sector information.
 23. Theterminal of claim 20, wherein the at least one processor is configuredto ascertain loading of each of multiple uplink channels based on thesector information and to select the uplink channel by considering theloading of each of the multiple uplink channels.
 24. The terminal ofclaim 20, wherein the at least one processor is configured to select theuplink channel from among the multiple uplink channels.
 25. The terminalof claim 20, wherein the sector information includes quality of service(QoS) information for multiple uplink channels available for use, andwherein the at least one processor is configured to select the uplinkchannel by considering the QoS information.
 26. The terminal of claim20, wherein the at least one processor is configured to send an accessrequest on the uplink channel to the base station.
 27. The terminal ofclaim 20, wherein the at least one processor is configured to establisha connection with the base station via the downlink channel and theuplink channel.
 28. The terminal of claim 20, wherein the at least oneprocessor is configured to ascertain at least one additional downlinkchannel from among the multiple downlink channels based on the frequencydistances, and to acquire each of the at least one additional downlinkchannel.
 29. The terminal of claim 28, wherein the at least oneprocessor is configured to select one downlink channel among thedownlink channel used to receive the sector information and the at leastone additional downlink channel, and to use the selected downlinkchannel for communication with the base station.
 30. The terminal ofclaim 20, wherein the sector information indicates center frequency ofeach of the multiple downlink channels, and wherein the at least oneprocessor is configured to tune a receiver to the center frequency ofeach downlink channel to determine channel conditions of the downlinkchannel.
 31. A method comprising: receiving sector information sent by abase station on a downlink channel, wherein the sector informationindicates multiple uplink channels and multiple downlink channelsavailable for use with the base station that sent the sectorinformation, and wherein the multiple available uplink channels and themultiple available downlink channels are in the same frequency band;ascertaining an uplink channel based on the sector information andfrequency distances between at least one of the multiple uplink channelsor the multiple downlink channels available for use with the basestation that sent the sector information; and using the uplink channelfor communication with the base station.
 32. The method of claim 31,further comprising: determining center frequency of the uplink channelbased on the frequency distances; and tuning a transmitter to the centerfrequency of the uplink channel.
 33. The method of claim 31, furthercomprising: determining loading of each of multiple uplink channelsbased on the sector information; and selecting the uplink channel byconsidering the loading of each of the multiple uplink channels.
 34. Themethod of claim 31, further comprising: ascertaining at least oneadditional downlink channel from among the multiple downlink channelsbased on the frequency distances; and acquiring each of the at least oneadditional downlink channel.
 35. An apparatus comprising: means forreceiving sector information sent by a base station on a downlinkchannel, wherein the sector information indicates multiple uplinkchannels and multiple downlink channels available for use with the basestation that sent the sector information, and wherein the multipleavailable uplink channels and the multiple available downlink channelsare in the same frequency band; means for ascertaining an uplink channelbased on the sector information and frequency distances between at leastone of the multiple uplink channels or the multiple downlink channelsavailable for use with the base station that sent the sectorinformation; and means for using the uplink channel for communicationwith the base station.
 36. The apparatus of claim 35, furthercomprising: means for determining center frequency of the uplink channelbased on the frequency distances; and means for tuning a transmitter tothe center frequency of the uplink channel.
 37. The apparatus of claim35, further comprising: means for determining loading of each ofmultiple uplink channels based on the sector information; and means forselecting the uplink channel by considering the loading of each of themultiple uplink channels.
 38. The apparatus of claim 35, furthercomprising: means for ascertaining at least one additional downlinkchannel from among the multiple downlink channels based on the frequencydistances; and means for acquiring each of the at least one additionaldownlink channel.
 39. A non-transitory computer-readable mediumincluding instructions stored thereon, comprising: a first instructionset for receiving sector information sent by a base station on adownlink channel, wherein the sector information indicates multipleuplink channels and multiple downlink channels available for use withthe base station that sent the sector information, and wherein themultiple available uplink channels and the multiple available downlinkchannels are in the same frequency band; a second instruction set forascertaining an uplink channel based on the sector information andfrequency distances between at least one of the multiple uplink channelsor the multiple downlink channels available for use with the basestation that sent the sector information; and a third instruction setfor directing use of the uplink channel for communication with the basestation.
 40. A terminal comprising: at least one processor configured toselect a first frequency channel from among at least one frequencychannel assigned to a sector for a first link, to select a secondfrequency channel from among multiple frequency channels assigned to thesector for a second link, and to establish a connection via the firstfrequency channel for the first link and the second frequency channelfor the second link, wherein the multiple frequency channels assigned tothe sector for the second link are in the same frequency band andcomprise one frequency channel designated in the sector as a primaryfrequency channel for the second link and at least one frequency channeldesignated in the sector as an auxiliary frequency channel for thesecond link, wherein the first link and the second link comprise anuplink and a downlink, wherein the first frequency channel is differentthan the second frequency channel, and wherein the selection of thefirst frequency channel is independent of the selection of the secondfrequency channel; and a memory coupled to the at least one processor.41. The terminal of claim 40, wherein the frequency band that includesthe multiple frequency channels for the second link further includes theat least one frequency channel for the first link.
 42. The terminal ofclaim 40, wherein the multiple frequency channels comprise the secondfrequency channel and a third frequency channel, and wherein a frequencydistance between the first and second frequency channels and a frequencydistance between the first and third frequency channels are different byat least a spacing between adjacent frequency channels for the secondlink.
 43. The terminal of claim 40, wherein the at least one processoris configured to obtain measurements for the at least one frequencychannel for the first link and to select the first frequency channelbased on the measurements.
 44. The terminal of claim 40, wherein the atleast one processor is configured to receive sector information from oneof the at least one frequency channel for the first link and to selectthe first frequency channel based on the sector information.
 45. Theterminal of claim 40, wherein the at least one processor is configuredto receive sector information from one of the at least one frequencychannel for the first link and to select the second frequency channelbased on the sector information.
 46. A method comprising: selecting afirst frequency channel from among at least one frequency channelassigned to a sector for a first link; selecting a second frequencychannel from among multiple frequency channels assigned to the sectorfor a second link, wherein the multiple frequency channels assigned tothe sector for the second link are in the same frequency band andcomprise one frequency channel designated in the sector as a primaryfrequency channel for the second link and at least one frequency channeldesignated in the sector as an auxiliary frequency channel for thesecond link, wherein the first link and the second link comprise anuplink and a downlink, wherein the first frequency channel is differentthan the second frequency channel, and wherein the selection of thefirst frequency channel is independent of the selection of the secondfrequency channel; and establishing a connection via the first frequencychannel for the first link and the second frequency channel for thesecond link.
 47. The method of claim 46, wherein the selecting the firstfrequency channel comprises obtaining measurements for the at least onefrequency channel for the first link, and selecting the first frequencychannel based on the measurements.
 48. The method of claim 46, whereinthe selecting the second frequency channel comprises receiving sectorinformation from one of the at least one frequency channel for the firstlink, and selecting the second frequency channel based on the sectorinformation.
 49. An apparatus comprising: means for selecting a firstfrequency channel from among at least one frequency channel assigned toa sector for a first link; means for selecting a second frequencychannel from among multiple frequency channels assigned to the sectorfor a second link, wherein the multiple frequency channels assigned tothe sector for the second link are in the same frequency band andcomprise one frequency channel designated in the sector as a primaryfrequency channel for the second link and at least one frequency channeldesignated in the sector as an auxiliary frequency channel for thesecond link, wherein the first link and the second link comprise anuplink and a downlink, wherein the first frequency channel is differentthan the second frequency channel, and wherein the selection of thefirst frequency channel is independent of the selection of the secondfrequency channel; and means for establishing a connection via the firstfrequency channel for the first link and the second frequency channelfor the second link.
 50. The apparatus of claim 49, wherein the meansfor selecting the first frequency channel comprises means for obtainingmeasurements for the at least one frequency channel for the first link,and means for selecting the first frequency channel based on themeasurements.
 51. The apparatus of claim 49, wherein the means forselecting the second frequency channel comprises means for receivingsector information from one of the at least one frequency channel forthe first link, and means for selecting the second frequency channelbased on the sector information.
 52. An apparatus comprising: at leastone processor configured to determine loading on each of multiple uplinkchannels that are in the same frequency band and available for use withthe apparatus, to send on a downlink channel sector information thatindicates the multiple uplink channels available for use with theapparatus and information for the loading on the multiple uplinkchannels available for use with the apparatus, and to communicate withat least one terminal on an uplink channel selected from the multipleuplink channels available for use with the apparatus based on theloading on the multiple uplink channels and further based on frequencydistances between the multiple uplink channels; and a memory coupled tothe at least one processor.
 53. The apparatus of claim 52, wherein theat least one processor is configured to send center frequency of atleast one of the multiple uplink channels.
 54. The apparatus of claim52, wherein the at least one processor is configured to send quality ofservice (QoS) information for the multiple uplink channels.
 55. Theapparatus of claim 52, wherein the at least one processor is furtherconfigured to determine loading on each of multiple downlink channelsthat are available for use with the apparatus and in the same frequencyband as the multiple available uplink channels, and to send on thedownlink channel information that indicates the multiple downlinkchannels available for use with the apparatus and information for theloading on the multiple downlink channels available for use with theapparatus.
 56. The apparatus of claim 52, wherein the at least oneprocessor is further configured to send on the downlink channelinformation that indicates downlink channels available for use with theapparatus.
 57. The apparatus of claim 52, wherein the at least oneprocessor is configured to send power backoffs for multiple downlinkchannels.
 58. The apparatus of claim 52, wherein the at least oneprocessor is configured to send frequency distances between multipledownlink channels and the downlink channel.
 59. A method comprising:determining loading on each of multiple uplink channels available foruse with a base station, wherein the multiple available uplink channelsare in the same frequency band; sending on a downlink channel sectorinformation that indicates the multiple uplink channels available foruse with the base station and information for the loading on themultiple uplink channels available for use with the base station; andcommunicating with at least one terminal on an uplink channel selectedfrom the multiple uplink channels available for use with the basestation based on the loading on the multiple uplink channels and furtherbased on frequency distances between the multiple uplink channels. 60.The method of claim 59, further comprising: sending center frequency ofat least one of the multiple uplink channels and quality of service(QoS) information for the multiple uplink channels.
 61. The method ofclaim 59, further comprising: determining loading on each of multipledownlink channels that are available for use with the base station andin the same frequency band as the multiple available uplink channels;and sending on the downlink channel information that indicates themultiple downlink channels available for use with the base station,information for the loading on the multiple downlink channels availablefor use with the base station, power backoffs for the multiple downlinkchannels available for use with the base station, and frequencydistances between the multiple downlink channels available for use withthe base station and the downlink channel.
 62. The method of claim 59,further comprising: sending on the downlink channel information thatindicates downlink channels available for use with the base station. 63.An apparatus comprising: means for determining loading on each ofmultiple uplink channels available for use with the apparatus, whereinthe multiple available uplink channels are in the same frequency band;means for sending on a downlink channel sector information thatindicates the multiple uplink channels available for use with theapparatus and information for the loading on the multiple uplinkchannels available for use with the apparatus; and means forcommunicating with at least one terminal on an uplink channel selectedfrom the multiple uplink channels available for use with the apparatusbased on the loading on the multiple uplink channels and further basedon frequency distances between the multiple uplink channels.
 64. Theapparatus of claim 63, further comprising: means for sending centerfrequency of at least one of the multiple uplink channels and quality ofservice (QoS) information for the multiple uplink channels.
 65. Theapparatus of claim 63, further comprising: means for determining loadingon each of multiple downlink channels that are available for use withthe apparatus and in the same frequency band as the multiple availableuplink channels; and means for sending on the downlink channelinformation that indicates the multiple downlink channels available foruse with the apparatus, information for the loading on the multipledownlink channels available for use with the apparatus, power backoffsfor the multiple downlink channels available for use with the apparatus,and frequency distances between the multiple downlink channels availablefor use with the apparatus and the downlink channel.
 66. The apparatusof claim 63, further comprising: means for sending on the downlinkchannel information that indicates downlink channels available for usewith the apparatus.
 67. A non-transitory computer-readable mediumincluding instructions stored thereon, comprising: a first instructionset for determining loading on each of multiple uplink channelsavailable for use with a base station, wherein the multiple availableuplink channels are in the same frequency band; a second instruction setfor sending on a downlink channel sector information that indicates themultiple uplink channels available for use with the base station andinformation for the loading on the multiple uplink channels availablefor use with the base station; and a third instruction set forcommunicating with at least one terminal on an uplink channel selectedfrom the multiple uplink channels available for use with the basestation based on the loading on the multiple uplink channels and furtherbased on frequency distances between the multiple uplink channels.
 68. Anon-transitory computer-readable medium including instructions storedthereon, comprising: a first instruction set for selecting a firstfrequency channel from among at least one frequency channel assigned toa sector for a first link; a second instruction set for selecting asecond frequency channel from among multiple frequency channels assignedto the sector for a second link, wherein the multiple frequency channelsassigned to the sector for the second link are in the same frequencyband and comprise one frequency channel designated in the sector as aprimary frequency channel for the second link and at least one frequencychannel designated in the sector as an auxiliary frequency channel forthe second link, wherein the first link and the second link comprise anuplink and a downlink, wherein the first frequency channel is differentthan the second frequency channel, and wherein the selection of thefirst frequency channel is independent of the selection of the secondfrequency channel; and a third instruction set for establishing aconnection via the first frequency channel for the first link and thesecond frequency channel for the second link.